The present embodiments relate generally to the field of medical devices, and more particularly, to an introducer sheath having a braided member.
Introducer sheaths are well-known for percutaneous vascular access and may comprise a suitable material such as polytetrafluoroethylene or fluorinated ethylene propylene. Such sheaths may comprise a relatively thin-wall construction, but may tend to kink. Increasing the thickness of the sheath wall minimally improves the level of kink resistance, which is still unacceptable. While positioned in a patient, the sheath may be bent or pinched off. A kinked sheath is unusable and cannot be straightened while positioned inside the body of a patient. Consequently, the sheath must be removed. Vascular access is then attempted at an alternative site, and the procedure is restarted, which causes an unacceptable time delay. Moreover, in some cases, an alternative site is not available for introducing another sheath.
One introducer sheath with improved kink resistance is disclosed in U.S. Pat. No. 5,380,304 to Parker (hereinafter “the '304 patent”). The introducer sheath comprises a coil having a plurality of turns, which is positioned around an inner tube. An outer tube is connected to the inner tube through the uniform spacing of the coil turns. As a result, the coil of the '304 patent reinforces the wall to provide an extremely kink-resistant and thin-walled introducer sheath. Preferably, the coil comprises a flat wire for minimizing the wall thickness of the sheath.
At least one other introducer sheath on the market has employed a braided member, which is disposed between inner and outer tubes of the sheath. The provision of a braided member advantageously may improve the overall torqueability characteristics of the introducer sheath. However, braided members typically are difficult to cut to length since the filaments may move with respect to one another, leading to partial unraveling and/or foreshortening. Moreover, the ends of the braided members may tend to flare in a radially outward direction, thereby causing difficulties in the assembly and manufacture of the introducer sheath.